Walk Off 300 Calories in 30 Minutes

You don't have to train for a Tough Mudder to work off extra pounds. "Interval walking is a great way to boost your metabolism and therefore burn calories," says Denise Austin, author of Side Effect: Skinny and a mom of two teenage daughters. Put on some comfortable exercise gear, bring along a watch or timer for the intervals, and try setting up a music playlist with a mix of 2-minute and 5-minute songs for this fat-blasting workout Austin designed.

Interval Walk

5 minutes: Walk at a nice pace, pumping your arms. For the last minute, stride with purpose.

2 minutes: Give it all you have, pumping your arms back and forth and walking as fast as you can.

5 minutes: Take it up another notch from the first 5 minutes' pace.

2 minutes: This is the big fat blast. Walk really fast, pumping those arms. If your knees are healthy, bring it to a jog.

5 minutes: Continue to walk quickly, making sure you feel comfortable and can talk as you walk.

2 minutes: Another big fat blast, stepping as fast as you can or jogging.

5 minutes: Continue to walk at a brisk pace, pumping your arms as you do so.

2 minutes: Now pick up the pace and give it 100%.

2 minutes: Slow down. Do arm circles as you walk slowly. This cool-down slowly reduces your heart rate and allows you to ease back into your normal routine.